The stink of ammonia in urine, sweat, and rotting meat repels humans, but many insects find ammonia alluring. Now, UConn researchers have figured out how the annoying insects smell it, a discovery that could lead to better ways to make them buzz off.

The sense of smell is enormously important. Mammals devote a third of their genetic code to odor receptors found in the nose, and have more than 1,000 different kinds that allow us to smell an estimated trillion different odors.

Flies don't have noses. Instead, they smell with their antenna. Each antenna is covered with tiny hairs called sensilla. Each sensilla contains a few neurons -- fly brain cells. Each neuron expresses one type of odor receptor, and they all fall into two main classes. Or so scientists thought.

But recent work by UConn neuroscientist Karen Menuz and her colleagues, reported online in June in Current Biology, identified a new type of odor neuron devoted to sniffing ammonia. And the receptor it uses is unlike any other odor receptor known.

Flies and other insects use the scent of ammonia to find food sources. Mosquitoes find humans to bite by following the faint scent of ammonia in our sweat, along with other clues. Many crop pests do the same, locating fruit and agricultural products to infest and consume. "When an odor binds to a receptor, the cell depolarizes, and sends a signal saying 'hey, the odor is here!' Insects are small, and odors come in plumes, so most insects will fly straight as long as the concentration is the same or growing. If they lose the odor plume, they'll do a casting behavior, flying in zig zags to find it," Menuz says.

Knowing exactly how the insects smell ammonia might yield effective ways to block them from following that scent plume -- and from finding us and our crops.

But figuring out exactly how and what a fly smells is tricky. Menuz and her colleagues are able to gently hold a fly down and use incredibly fine pieces of glass to probe individual neurons in sensilla on the fly's antenna. Then they let the ammonia waft.

They probed all three types of scent neurons in the flies' sensilla, but they didn't respond to ammonia. But the fly was obviously smelling it. So the researchers realized there had to be a fourth scent neuron they hadn't known was there. And they found it -- but it didn't seem to have the usual odor receptors on it. It was covered in ammonia transporter (Amt) a molecule that is known to allow ammonia in and out of cells.

No one had ever known a transporter molecule to also act as an odor receptor. But there it was. When they selectively killed off only that type of neuron, the flies did not respond to ammonia at all. And when the team forced scent neurons that don't normally respond to ammonia to express Amt on their surfaces, those neurons began responding to ammonia, too.

The team hopes to learn whether mosquitoes use the same system to smell ammonia. If it's used by both mosquitoes and flies, it's a good bet the Amt receptor-as-sniffer is used by all insects, and developing ways to block Amt could be an effective way to protect people and crops from pests attracted to ammonia.

Copied From: Science Daily

Current rates of plastic emissions globally may trigger effects that we will not be able to reverse, argues a new study by researchers from Sweden, Norway and Germany published on July 2nd in Science. According to the authors, plastic pollution is a global threat, and actions to drastically reduce emissions of plastic to the environment are "the rational policy response."

Plastic is found everywhere on the planet: from deserts and mountaintops to deep oceans and Arctic snow. As of 2016, estimates of global emissions of plastic to the world's lakes, rivers and oceans ranged from 9 to 23 million metric tons per year, with a similar amount emitted onto land yearly. These estimates are expected to almost double by 2025 if business-as-usual scenarios apply.

"Plastic is deeply engrained in our society, and it leaks out into the environment everywhere, even in countries with good waste-handling infrastructure," says Matthew MacLeod, Professor at Stockholm University and lead author of the study. He says that emissions are trending upward even though awareness about plastic pollution among scientists and the public has increased significantly in recent years.

That discrepancy is not surprising to Mine Tekman, a PhD candidate at the Alfred Wegener Institute in Germany and co-author of the study, because plastic pollution is not just an environmental issue but also a "political and economic" one. She believes that the solutions currently on offer, such as recycling and cleanup technologies, are not sufficient, and that we must tackle the problem at its root.

"The world promotes technological solutions for recycling and to remove plastic from the environment. As consumers, we believe that when we properly separate our plastic trash, all of it will magically be recycled. Technologically, recycling of plastic has many limitations, and countries that have good infrastructures have been exporting their plastic waste to countries with worse facilities. Reducing emissions requires drastic actions, like capping the production of virgin plastic to increase the value of recycled plastic, and banning export of plastic waste unless it is to a country with better recycling" says Tekman.

A poorly reversible pollutant of remote areas of the environment

Plastic accumulates in the environment when amounts emitted exceed those that are removed by cleanup initiatives and natural environmental processes, which occurs by a multi-step process known as weathering.

"Weathering of plastic happens because of many different processes, and we have come a long way in understanding them. But weathering is constantly changing the properties of plastic pollution, which opens new doors to more questions," says Hans Peter Arp, researcher at the Norwegian Geotechnical Institute (NGI) and Professor at the Norwegian University of Science and Technology (NTNU) who has also co-authored the study. "Degradation is very slow and not effective in stopping accumulation, so exposure to weathered plastic will only increase," says Arp. Plastic is therefore a "poorly reversible pollutant," both because of its continuous emissions and environmental persistence.

Remote environments are particularly under threat as co-author Annika Jahnke, researcher at the Helmholtz Centre for Environmental Research (UFZ) and Professor at the RWTH Aachen University explains:

"In remote environments, plastic debris cannot be removed by cleanups, and weathering of large plastic items will inevitably result in the generation of large numbers of micro- and nanoplastic particles as well as leaching of chemicals that were intentionally added to the plastic and other chemicals that break off the plastic polymer backbone. So, plastic in the environment is a constantly moving target of increasing complexity and mobility. Where it accumulates and what effects it may cause are challenging or maybe even impossible to predict."

A potential tipping point of irreversible environmental damage

On top of the environmental damage that plastic pollution can cause on its own by entanglement of animals and toxic effects, it could also act in conjunction with other environmental stressors in remote areas to trigger wide-ranging or even global effects. The new study lays out a number of hypothetical examples of possible effects, including exacerbation of climate change because of disruption of the global carbon pump, and biodiversity loss in the ocean where plastic pollution acts as additional stressor to overfishing, ongoing habitat loss caused by changes in water temperatures, nutrient supply and chemical exposure.

Taken all together, the authors view the threat that plastic being emitted today may trigger global-scale, poorly reversible impacts in the future as "compelling motivation" for tailored actions to strongly reduce emissions.

"Right now, we are loading up the environment with increasing amounts of poorly reversible plastic pollution. So far, we don't see widespread evidence of bad consequences, but if weathering plastic triggers a really bad effect we are not likely to be able to reverse it," cautions MacLeod. "The cost of ignoring the accumulation of persistent plastic pollution in the environment could be enormous. The rational thing to do is to act as quickly as we can to reduce emissions of plastic to the environment."

Copied From: Science Daily
Source: Stockholm University

I wanted to take a moment to provide my thoughts about this blog, as well as the developer. This blog started out on a small scale and has turned out to be a full fledged blog with many bells and whistles. There have been many trials and errors but the developer (Terry) persevered and it has now evolved into what it is today. Another purpose for this post is to experience first hand how to post an article on someone else's blog. You have to admit that is not the usual way a blog site is run. Just another reason to give this a try. This last part is aimed at Terry himself...I wonder if the Latest Topics list in the right hand panel could be set up as a drop down list? I believe that it would make the panel seem "tighter" and prevent the need to scroll down to see what else is in the panel. Keep in mind this is an opinion and may not even be possible as I don't have the coding skills needed to determine the viability of doing so. Congratulations on a great looking blog.

When people see a toothbrush, a car, a tree -- any individual object -- their brain automatically associates it with other things it naturally occurs with, allowing humans to build context for their surroundings and set expectations for the world.

By using machine-learning and brain imaging, researchers measured the extent of the "co-occurrence" phenomenon and identified the brain region involved. The findings appear in Nature Communications.

"When we see a refrigerator, we think we're just looking at a refrigerator, but in our mind, we're also calling up all the other things in a kitchen that we associate with a refrigerator," said corresponding author Mick Bonner, a Johns Hopkins University cognitive scientist. "This is the first time anyone has quantified this and identified the brain region where it happens."

In a two-part study, Bonner and co-author, Russell Epstein, a psychology professor at the University of Pennsylvania, used a database with thousands of scenic photos with every object labeled. There were pictures of household scenes, city life, nature -- and the pictures had labels for every mug, car, tree, etc. To quantify object co-occurrences, or how often certain objects appeared with others, they created a statistical model and algorithm that demonstrated the likelihood of seeing a pen if you saw a keyboard, or seeing a boat if you saw a dishwasher.

With these contextual associations quantified, the researchers next attempted to map the brain region that handles the links.

While subjects were having their brain activity monitored with functional magnetic resonance imaging, or fMRI, the team showed them pictures of individual objects and looked for evidence of a region whose responses tracked this co-occurrence information. The spot they identified was a region in the visual cortex commonly associated with the processing of spatial scenes.

"When you look at a plane, this region signals sky and clouds and all the other things,quot; Bonner said. "This region of the brain long thought to process the spatial environment is also coding information about what things go together in the world."

Researchers have long-known that people are slower to recognize objects out of context. The team believes this is the first large-scale experiment to quantify the associations between objects in the visual environment as well as the first insight into how this visual context is represented in the brain.

"We show in a fine-grained way that the brain actually seems to represent this rich statistical information," Bonner said.

Copied From: Science Daily
Source: Johns Hopkins University